Exemplary embodiments of the present invention relate to a method for automatically generating a three-dimensional reference model as terrain information for an imaging device with a predetermined field of view, in particular for a seeker head of an unmanned missile equipped with a camera.
Modern missile systems frequently use models of a target for target recognition and target tracking. These models represent a description of the target structure and optionally the target environment, and are generated before deployment in a mission planning. To allow flexible selection of the approach profiles and to ensure a high strike accuracy, these models must also define the three-dimensional structure of the target and the target environment.
Practice has shown that the two-dimensional structure of the target and the target environment in the horizontal dimension can be obtained accurately from aerial photographs and satellite images, but that it is often difficult to obtain good and sufficient information on the height structure. Often only imprecise and roughly scanned height data are available for the terrain, so that height values have to be interpreted over large intervals compared to target dimensions. Such data are often missing for buildings, bridges and the like as three-dimensional target objects on the terrain, and therefore have to be estimated. Errors occurring in this estimate have a negative effect on strike accuracy and thus on the success of a mission. It is therefore desirable to have methods available that generate good and reliable three-dimensional information from reconnaissance data.
European Patent Document No. EP 2 060 873 A2 discloses a method for line-based three-dimensional reconstruction of terrain data from image sequences, which were taken with an image capturing device of a missile. In this method, two-dimensional line segments are extracted from the individual images, tracked via the image sequence, and three-dimensional line segments are then established from the tracks of the line segments and the navigation data of the reconnaissance platform. In addition to the line segments, intersection points of such segments are also taken into consideration. The result is a wire-frame model of a scene, composed of three-dimensional line segments and topological information about intersections of segments of this type. Furthermore, for each object established thereby, an estimate of accuracy is carried out in the form of a covariance matrix for the parameters involved. This method had not yet been used to produce reference models for missile missions.
With prior methods used for defining a target object for missile missions, a processor has had to manually extract two-dimensional lines of the target structure from a two-dimensional original, for example, an air reconnaissance photograph, and individually provide them with additional height data.